Field of the Invention
The present invention relates to an automated analyzer and a method for lifting and lowering a rod-like member in the automated analyzer. Particularly, the present invention relates to a method for lifting and lowering a stirring bar that performs stirring, or a rod-like member such as a probe that performs injection/suction.
Description of the Related Art
For example, a biochemical analyzer for analyzing various components contained in a specimen such as blood or urine is known as the automated analyzer. In the biochemical analyzer, a reagent corresponding to an item of analysis and a specimen are mixed and caused to react with each other within a reaction container. In addition, the biochemical analyzer analyzes a specific component of the specimen by irradiating the specimen reacting with a reagent, with light and using the photometry results.
Such a biochemical analyzer includes a dispensing mechanism in which a liquid such as a specimen or a reagent is dispensed between two containers, and a stirring mechanism in which a mixed liquid of the dispensed regent and specimen is uniformly stirred. The dispensing mechanism includes a probe for dispensing a liquid. The stirring mechanism includes a stirring bar that uniformly stirs the mixed liquid. Furthermore, the biochemical analyzer includes a cleaning mechanism for cleaning a liquid such as the specimen or reagent which adheres to a tip portion of the rod-like member such as the probe or stirring bar.
At the dispensing operation, first, a probe of the dispensing mechanism moves down to a liquid surface of a reagent which is stored in a reagent container, and after a tip of the probe reaches a desired depth under the liquid surface of the reagent, a suction operation of the reagent by the probe is conducted. Next, while holding the sucked reagent in the probe, there is performed an operation of moving the probe from the reagent container to the targeted reaction container. In addition, the reagent in the probe is discharged into a reaction solution which is stored in the reaction container.
Incidentally, during the above dispensing procedures, excessive liquid droplets adhere to the tip portion of the probe since the probe lifts and lowers relative to the container and the tip of the probe makes contact with the specimen, reagent or cleaning liquid. In addition, when the excessive liquid droplets are admixed to, for example, the reaction container, there is unevenness in the absolute amount of the dispensed liquid. Furthermore, during the cleaning procedure, when the cleaning liquid adhering to the tip of the probe is admixed to, for example, a reagent container or the reaction container, the reagent or the reaction solution is diluted. Thereby, accuracy in analysis of the automated analyzer is lowered. In addition, during the movement of the probe, contamination of machinery is also generated due to scattering the excessive liquid droplets.
As a countermeasure for reducing such liquid droplets adhering to the tip portion of the rod-like member, Japanese Patent Laid-Open Publication No. 09-184846 proposes a liquid sample dispensing device having a small amount discharging means that discharges a small amount of liquid and a nozzle moving mechanism that lifts and lowers nozzles. Specifically, the liquid droplets adhering to the nozzle are removed by rapidly accelerating and rapidly decelerating the nozzles when lifting and lowering the nozzles by the nozzle moving mechanism.
Furthermore, in Japanese Patent Laid-Open Publication No. 2010-271203, there is proposed a sampling method which has a step of moving a dispensing nozzle up at a given rate, and a step of moving the dispensing nozzle up at a rate larger than the given rate after detecting removal of the dispensing nozzle from the sample. Specifically, the liquid droplets adhering to the nozzle are reduced by changing the pattern of the upward motion of the nozzle before and after the removal of the nozzle tip portion from the liquid.